Adding one playlist to another adds only 100 items

Checklist

• I am able to reproduce the bug with the latest version given here: CLICK THIS LINK.
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• This issue contains only one bug.
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Affected version

0.28.0, 0.28.1-rc

Steps to reproduce the bug

1. Open playlist with more than 100 videos (example https://www.youtube.com/playlist?list=PL9ECA8AEB409B3E4F)
2. Press 3 dots menu in top left corner
3. Press add to playlist
4. (Optionally) select new playlist
5. New playlist contains 100 items only

But if you scroll the playlist before step 3. There will be more than 100 items. Not guaranteed that all videos but surely more than 100

Expected behavior

obvious

Actual behavior

No response

Screenshots/Screen recordings

No response

Logs

No response

Affected Android/Custom ROM version

Seems to not matter

Affected device model

Seems to not matter

Additional information

Closely related to #12152 and probably has the same cause

[absurdlylongusername]

I believe #875 is the original issue for this problem, so this is basically a duplicate. This is an old problem due to the fact that the code isn't currently extracting all the videos in the playlist when it adds to queue or adds to playlist or similar.

It only adds what it has extracted so far. To get the whole playlist requires network requests, and depending on the service can be fast or slow (although it's fast in general, but if the playlist is long enough it might take a few seconds, since even on YT UI loading a large playlist takes a while).

The discussion there sheds more light on this.